Seoul citizens walk past a notification that says a heat wave warning has been issued in Myeong-dong on Sunday. (Yonhap) South Korea can expect high day and nighttime temperatures until early next month, with Monday's temperature projected to reach 39 degrees Celsius in some regions.The Korea Meteorological Administration issued a heat wave emergency warning for several southeastern regions, including Gyeongsan, Pohang, Gyeongju cities and Goryeong and Cheongdo counties of North Gyeongsang Province; Yangsan, Gimhae, Miryang cities and Euiryeong, Haman, Changnyeong, Hapcheon counties of South Gyeongsang Province; and the Daegu metropolis.The heat wave emergency warning is the highest of the new three-tiered system implemented this year, issued when the temperature is expected to reach 38 degrees Celsius or higher after remaining above 35 C for two consecutive days. It is also issued when the apparent temperature is forecast to be at least 38 C.Temperatures in Seoul and Incheon are expected to be as high as 33 C on Monday, with Gwangju and Busan expecting highs of 35 C. The daily high is expected to be between 31 and 37 C for most regions, with the apparent temperature rising to at least 33 C.High temperatures to persist for over a weekSimilarly high temperatures are expected across the country for the time being, according to the weather authorities.The KMA projected morning temperatures to be between 24 and 26 C, while daytime temperatures are expected to be between 32 to 39 C until Aug. 6."Tropical nights and the heat wave will continue at least until early next month," the KMA said in its forecast.Tropical nights occur when the overnight low between 6 p.m. and 9 a.m. remains at or above 25 C.The peninsula can expect some rain in Seoul, Incheon, Gyeonggi Province, Gangwon Province, northern North Gyeongsang Province and some parts of North and South Chungcheong Provinces.However, the rainfall will only have a temporary effect on bringing temperatures down, the KMA said.Thunderstorms are expected in some parts of the East Sea and the West Sea until Tuesday, along with heavy fog.